With \(g_{+}(0)\)  in hand, the other unknown, i.e. \(A_0(0)\) , can be expressed in terms of it as [1]},
\(A_0(0) & = & \left( \frac{1-M_{V}^2/M_{B}^2}{1+M_{V}^2/M_{B}^2}+\frac{M_B}{M_V} \right)g_{+}(0)\ .\) 
